From 5c3396c6977fcda6eeacc70cd7073fd4d60a512c Mon Sep 17 00:00:00 2001
From: gammazero <gammazero@users.noreply.github.com>
Date: Fri, 15 Sep 2023 01:55:58 -0700
Subject: [PATCH] Update dtsync head error message

If the head protocol is not supported, only an error that contains the correct protocol name.
---
 dagsync/dtsync/head/head.go | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/dagsync/dtsync/head/head.go b/dagsync/dtsync/head/head.go
index f6ec73e..af2c10a 100644
--- a/dagsync/dtsync/head/head.go
+++ b/dagsync/dtsync/head/head.go
@@ -82,10 +82,11 @@ func QueryRootCid(ctx context.Context, host host.Host, topic string, peerID peer
 					// If protocol ID is wrong, then try the previous protocol ID.
 					var errNoSupport multistream.ErrNotSupported[protocol.ID]
 					if errors.As(err, &errNoSupport) {
+						origErr := err
 						oldProtoID := previousProtocolID(topic)
 						conn, err = gostream.Dial(ctx, host, peerID, oldProtoID)
 						if err != nil {
-							return nil, err
+							return nil, origErr
 						}
 						log.Infow("Peer head CID server uses old protocol ID", "peer", peerID, "proto", oldProtoID)
 					} else {